Gas-phase brominated powdered activated carbons (e.g., B-PAC, produced by Albemarle Corporation) are effective sorbents for mercury emission control in gaseous streams containing mercury. Among various references to the synthesis and usage of brominated powdered activated carbon sorbents for mercury is U.S. Pat. No. 6,953,494 to Nelson, Jr.
About 70% to about 100% of the bromine in commercially-available brominated carbonaceous sorbents is water leachable (WL). This leachable bromine negatively influences the performance of the brominated carbonaceous sorbents in semi-wet SO2 scrubbers such as Circulation Absorber Scrubbers (CDS), high moisture scrubbers such as Spray Dryer Absorbers (SDA), and in fully-wet SO2 scrubbers because the sorbent is recycled to the system. Also, the dissolved bromine species could have negative impacts on the discharged wastewaters from these SO2 scrubbers.
It would be of considerable advantage if a way could be found for effectively increasing the amount of non-water-leachable (NWL) components and/or species of brominated carbonaceous sorbents that remain present in the sorbent after exposure to water or aqueous suspensions or solutions, i.e., a way of reducing the amount of bromine-containing components and/or species originally present in the sorbent that are removed from the sorbent by or after exposure to water or aqueous systems during handling and/or usage. If this objective could be accomplished, this would enhance the utility of such sorbents in semi-dry CDSes, high moisture SDAs, and in fully wet SO2 scrubbers. Additionally, such sorbents would be usable in plants that are equipped with a wet electrostatic precipitator (WESP) as a particulate control device.
This invention is believed to have successfully accomplished the foregoing objectives in an effective and economically efficient manner.